The highest incidence of relapse to smoking occurs within the first 2 weeks of a cessation attempt. This initial phase of smoking cessation is marked by memory dysfunction and increased stress reactivity. Many smokers are not able to overcome these symptoms, and they relapse to smoking shortly after trying to quit. Results of recent studies show that insulin in the Central Nervous System dampens stress response and improves memory function in both healthy subjects as well as Alzheimer's disease patients. Insulin in these studies was delivered to the Central Nervous System intranasally, and no significant episodes of hypoglycemia were observed. Intranasal insulin has never been studied in nicotine dependent research participants. As memory dysfunction and increased stress reactivity are important aspects of nicotine withdrawal, intranasal insulin's positive effect on these two domains may improve smoking cessation treatment outcomes. In a randomized, double-blind, Phase I study (N=70), we will be testing a hypothesis that intranasal insulin will: 1 improve episodic memory dysfunction, 2. dampen stress response, 3. be safe and feasible to administer to acutely abstinent smokers. Increasing brain insulin levels by intranasal administration may be a promising approach for relieving symptoms of nicotine withdrawal.